Rats show empathy, will come to the aid of other rats

Rats will deliberately free trapped companions and may even share food with …

Empathy is the ability to feel others' pain or distress; we feel bad when someone else feels bad. It’s what motivates us to give a few dollars to the homeless man on the corner, donate our time to a worthy cause, or hug a friend who has just been dumped. Scientists used to believe that empathy was unique to humans and was one of the traits that actually distinguished us from other species. Recently, however, there is increasing evidence for empathy in several species, most notably other primates.

Now, new research in Science suggests that rats are capable of empathy. The study tested how rats responded when their fellow rats were trapped, and found that they would not only spend time and energy deliberately helping their trapped companions, but they would even share food after liberating them.

The experiments were conducted in a square arena with a small cage at its center. In some trials, the center cage had a rat trapped inside, and in some trials it was empty. Another rat was released into the arena, and it could decide whether or not to free the trapped rat by rotating the door on its cage. This situation was repeated for 12 days, and the researchers noted not only whether or not the free rat opened the cage, but also its activity patterns during the entire trial.

The free rats were noticeably agitated when there was a rat trapped in the cage, and tended to circle the center of the arena, dig at the cage, and call to the trapped rat; when the cage was empty, these behaviors were absent. Over the course of the experiment, the rats learned to open the cage, and became much faster at doing so. A much higher percentage of the rats that were inside the arena with a trapped rat opened the cage (23 out of 30), compared to the rats that were in the arena with an empty cage (5 out of 40). Clearly, the rats were much more motivated to open the cage when there was a companion stuck inside.

Interestingly, female rats were more likely to open the cage with a trapped rat than males were; during the 12 trials, 100 percent of the females became door-openers, while just over 70 percent of the males did. The females were also quicker to open the door than males were, and were more active than males before liberating the other rat. While there certainly are other explanations, it’s possible that in rats, as in humans, females tend to be more empathetic than males.

The researchers then added another closed cage into the arena; this one was filled with chocolate chips. The rats were just as likely to open the cage with the rat as they were to open the cage with the chocolate, suggesting that the motivation to free a trapped companion is about as strong as the motivation to eat the chocolate (for those of you who don’t know, rats really like chocolate). Additionally, in more than half of the trials, the free rats shared the chocolate with the trapped rat after freeing it. The free rats actually ate fewer chocolate chips when there was another rat in the arena than they did when they were alone, indicating a willingness to share the bounty.

It’s important to note that in these trials, we don’t know whether the rats were trying to alleviate the trapped rats' distress, or to make themselves feel better about the situation. A comparison to human behavior provides a similar question: when we give to charity, are we doing so to actually help those less fortunate than us, or to eliminate the negative feelings we have when we think about the plights of others? While this is an important distinction to make, both motivations still fall under the definition of empathy. In either case, the rats were negatively affected by the trapped rats’ situation, and were acting deliberately to eliminate the source of distress.

There is much more work to be done on this topic, and this type of research always raises just as many questions as it answers. But well-designed studies like these contribute greatly to what we know about empathy in other animals. The more we learn, the more we understand that our ability to respond emotionally to others' distress doesn’t separate us from other species; it reminds us how similar we are to them.

Interestingly, female rats were more likely to open the cage with a trapped rat than males were; during the 12 trials, 100 percent of the females became door-openers, while just over 70 percent of the males did. The females were also quicker to open the door than males were, and were more active than males before liberating the other rat. While there certainly are other explanations, it’s possible that in rats, as in humans, females tend to be more empathetic than males.

BUT THAT'S THE BREADWINNER TRAPPED IN THERE!!

Now does the paper address if females released trapped females faster than if it was a trapped male? The other way around?

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While this is an important distinction to make, both motivations still fall under the definition of empathy. In either case, the rats were negatively affected by the trapped rats’ situation, and were acting deliberately to eliminate the source of distress.

Killing the trapped rat would alleviate the negative feelings and kept any food for themselves.

Did the rats know each other ? How wonder how the numbers would change if the rats were all family.

That's my question too, but the paper doesn't seem to mention the issue (after a quick search for some keywords). I'm not an expert on the matter, but I am aware that in some past studies looking into animals one another, it tends to happen when they are related (kin selection). Either way, it's a fascinating social behavior in rats.

This sort of behaviour has been rumoured to exist in a close relative of the rat, the lawyer, although to date no one has observed it in a controlled environment where all monetary rewards had been eliminated.

In order to test the theory the researchers created moneyless environments. Normally these are perfectly stable, but every time they introduce lawyers they sue the researchers on behalf of each other on a "no win no fee" basis. This is futile of course. When the unsuccessful law suits start to mount up this activity winds down, but only to be replaced malpractice suites over the failed researcher suites. After a time this also winds down because again the lawyers run into the central conundrum: there is no point suing anyone when no one has money.

Researchers had hypothesised the lawyers would come to understand the pointlessness of continued attacking each other when there was no money available, and instead settle down to the normal patterns of altruism seen in other professions. So far this has never happened. Instead the lawyers retire to the bench, and order the researchers to pay them a suitable stipendiary in return for keeping the peace.

That was possibly the most well-written summary/analysis of a scientific paper that I've ever read.

I agree, it was very well written.

Any animal that shows Empathy is cool in my books. I start to think that if Humans were put in this trial, would the captive get any chocolate at all? The sense of entitlement in Humans is too high, pride would take over and they’d think the chocolate was deservedly theirs.

I've got a big bunch of guinea pigs at home, and time ago I observed an interesting behaviour: I had to separate a pair from the main group for some time, and when I tried to join one of them again to it she was attacked and a fight started. There's a fearful one, Smith, that was terrified in the corner, and suddenly his mother approached and started nibbling her ear, as if comforting her.

To me, it looks like that comforting a companion is probably a too complex behaviour for such animals, but Smithy liked it and calmed down, so I'm still wondering if that was the intention of her mother.

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when we give to charity, are we doing to so actually help those less fortunate than us, or to eliminate the negative feelings we have when we think about the plights of others?

I actually tend to think there's no distinction, for me both views lie in the same motivation. When we see somebody suffering we suffer; if their suffering stops, so does our. If we were happy when somebody suffers, would we try to stop it?

That was possibly the most well-written summary/analysis of a scientific paper that I've ever read.

I agree, it was very well written.

Any animal that shows Empathy is cool in my books. I start to think that if Humans were put in this trial, would the captive get any chocolate at all? The sense of entitlement in Humans is too high, pride would take over and they’d think the chocolate was deservedly theirs.

I suppose you're joking, but there have been plenty of economics and psychology tests to this effect.

I'm not an expert on the matter, but I am aware that in some past studies looking into animals one another, it tends to happen when they are related (kin selection).

Rats are somewhat social in their behaviour and any random rat in a given range has a fair chance of being related to any other rat it encounters (same with humans over most of our history) so kin selection is likely to play a significant role in this.

Rats that helped each other out in the past were more likely to have genes that would get passed on by the (likely related) rat they helped out, producing a race of rats today more heavily descended from helpers than non-helpers.

The topic for this story is misleading. It is clearly stated in the actual write up that it is not proper to compare this to human behavior. We do not know what factors influenced the rats to open the cage and it is a big jump to say that it was Empathy.

That was possibly the most well-written summary/analysis of a scientific paper that I've ever read.

I agree, it was very well written.

Any animal that shows Empathy is cool in my books. I start to think that if Humans were put in this trial, would the captive get any chocolate at all? The sense of entitlement in Humans is too high, pride would take over and they’d think the chocolate was deservedly theirs.

I suppose you're joking, but there have been plenty of economics and psychology tests to this effect.

Well, I don't study behaviourism, but reality has taught me that I’m only at the least maybe 30% - 50% joking.

While this is an important distinction to make, both motivations still fall under the definition of empathy. In either case, the rats were negatively affected by the trapped rats’ situation, and were acting deliberately to eliminate the source of distress.

Killing the trapped rat would alleviate the negative feelings and kept any food for themselves.

The topic for this story is misleading. It is clearly stated in the actual write up that it is not proper to compare this to human behavior. We do not know what factors influenced the rats to open the cage and it is a big jump to say that it was Empathy.

I know, right? Same with humans. We don't know what factors motivates them to help others.

You know why the rat opened the cage door? To see another rat. That's all this experiment shows. As long as we are making up rat emotions, let's try this one out - I am a bored rat in a cage. I can let another rat in here with me and we can have a little rat party. Who knows, with enough rats, we might even be able to break out of here. Therefore I conclude that rats have the human trait of conspiring.

By the way, whatever you do, NIMH, don't give them the intelligence boosting drugs...

Outside of this study, I have five rats as pets and they are the coolest pets I have (out of a cockatiel, a turtle, a dog, a cat, a leopard gecko, and some other lizard we picked up and brought across state lines so we could break the law). They're intelligent, comforting, inquisitive, furry, and have little hands that grasp your fingers when they're grooming you in thanks for the cheese you just gave them.

Course, the little hands are a problem when you walk by their cage and they're all five lined up begging to be let out, their hands grasping the bars like prisoners who've been denied food and water for weeks on end...

"A comparison to human behavior provides a similar question: when we give to charity, are we doing to so actually help those less fortunate than us, or to eliminate the negative feelings we have when we think about the plights of others? While this is an important distinction to make, both motivations still fall under the definition of empathy."

Would it be more correct to say that both motivations fall under the definition of altruism, but only the former counts as empathy?

You know why the rat opened the cage door? To see another rat. That's all this experiment shows. As long as we are making up rat emotions, let's try this one out - I am a bored rat in a cage. I can let another rat in here with me and we can have a little rat party. Who knows, with enough rats, we might even be able to break out of here. Therefore I conclude that rats have the human trait of conspiring.

By the way, whatever you do, NIMH, don't give them the intelligence boosting drugs...

This is pretty much what I got from it, too. Who knows, maybe they're wired to help other rats in order to perpetuate the species. The gender difference and food sharing both seem to make sense in that light, also. There are plenty of reasons to open the door besides empathy.

Did the rats know each other ? How wonder how the numbers would change if the rats were all family.

That's my question too, but the paper doesn't seem to mention the issue (after a quick search for some keywords). I'm not an expert on the matter, but I am aware that in some past studies looking into animals one another, it tends to happen when they are related (kin selection). Either way, it's a fascinating social behavior in rats.

According to the abstract, the rats were cage mates. The paper states that they were housed together for 2 weeks prior to the study.

This is pretty much what I got from it, too. Who knows, maybe they're wired to help other rats in order to perpetuate the species. The gender difference and food sharing both seem to make sense in that light, also. There are plenty of reasons to open the door besides empathy.

Isn't being "wired to help other rats" merely a neurobiological description of empathy? Note that evolutionarily, there is no particular reason rats would be expected to have an interest in "perpetuating the species." Natural selection tends to favor gene alleles that support their own propagation over competing alleles, not ones that help everybody.

On the other hand, "being wired to help other rats" could be a way to facilitate reciprocal altruism. Even better would be if rats are able in some way to recognize other rats that are "wired to help," to inhibit invasion of "jerk" genotypes that accept help but don't offer it. These rats had been living together for a couple of weeks, which might be enough time to recognize whether one's cagemate is a helper or a jerk. It would be interesting to look at stranger rats, although this would be subject to the confound that rats tend to be particularly interested in strangers, which would be another possible motivation for opening the door.

Of course, these are lab rats, which are likely less genetically diverse than wild ones, being the outcome of many generations of selection for tractability (and inability to escape).

Isn't being "wired to help other rats" merely a neurobiological description of empathy? Note that evolutionarily, there is no particular reason rats would be expected to have an interest in "perpetuating the species." Natural selection tends to favor gene alleles that support their own propagation over competing alleles, not ones that help everybody.

On the other hand, "being wired to help other rats" could be a way to facilitate reciprocal altruism. Even better would be if rats are able in some way to recognize other rats that are "wired to help," to inhibit invasion of "jerk" genotypes that accept help but don't offer it. These rats had been living together for a couple of weeks, which might be enough time to recognize whether one's cagemate is a helper or a jerk. It would be interesting to look at stranger rats, although this would be subject to the confound that rats tend to be particularly interested in strangers, which would be another possible motivation for opening the door.

Of course, these are lab rats, which are likely less genetically diverse than wild ones, being the outcome of many generations of selection for tractability (and inability to escape).

Well, I didn't really mean "the species" exactly. More or less what I meant was that if they let another rat out of the cage, that might give them a chance to reproduce. The study notes that females are more likely to open the cages, but it doesn't mention if it was a male or female in the cage, so it's hard to tell from that alone.

My belief is that animals do empathy at times, I just don't think this study proves it one way or the other. It shows that rats will free other rats, but for what purpose? Reproduction? Companionship? Simple curiosity? There's no real way of knowing, and the study doesn't seem to discount the fact that rats are naturally social, curious creatures.

"It’s important to note that in these trials, we don’t know whether the rats were trying to alleviate the trapped rats' distress, or to make themselves feel better about the situation. A comparison to human behavior provides a similar question: when we give to charity, are we doing to so actually help those less fortunate than us, or to eliminate the negative feelings we have when we think about the plights of others?"

Humans are not a uni-motivational species. Perhaps neither are the rats.

‘You have heard that it was said, “You shall love your fellow rat and hate the enemy cat.” But I say to you, Love the cat and pray for those dogs which persecute you, so that you may be the brood of your Father in heaven; for he makes his sun rise on the evil and on the good, and sends rain on the righteous and on the unrighteous. For if you love those who love you, what reward do you have? Do not even the cats do the same? And if you greet only fellow rats what more are you doing than others? Do not even the dogs do the same? Be perfect, therefore, as your heavenly Father is perfect.

The topic for this story is misleading. It is clearly stated in the actual write up that it is not proper to compare this to human behavior. We do not know what factors influenced the rats to open the cage and it is a big jump to say that it was Empathy.

I know, right? Same with humans. We don't know what factors motivates them to help others.

Stop trolling, please.

The fact of the matter is that Empathy has a specific meaning that we cannot say for certain applies to these rats. I didn't say that it absolutely is not Empathy, I merely pointed out that it is a mistake to assume that it is. For all we know, the rats became more curious about what was inside the cage because the other rat was in it.

As with most science, it is improper to assume that we know something without significant evidence. The only evidence we have here is the rats behavior in one specific set of circumstances, it is not enough to extrapolate reasoning.

If you honestly think that I am trolling, I think it is apparent that you don't know what that means. Your response is beneath the level of discussion that I am used to seeing on Ars Technica.

Kate Shaw Yoshida / Kate is a science writer for Ars Technica. She recently earned a dual Ph.D. in Zoology and Ecology, Evolutionary Biology and Behavior from Michigan State University, studying the social behavior of wild spotted hyenas.